If there is iron/steel pipe anywhere in the system it can do it. Some of the cheap inlet/outlet insulating nipples deterioate. Anode might be used up. Rotted hose on washer,but that wouldn't mess with kitchen facuet unless mixer valve on washer was bad. Have you drained and/or flushed water heater? Sediment is usually red but I suppose it could be black with different chemicals in water.

All the plumbing is copper, including the IN and OUT to and from the water heater. Washing machine hose is three years old, kitchen faucet is 18 months old from a recent remodel.

I probably need to drain/flush the water heater, since it's three years old, and see if that helps before I call in a plumber and get charged a small fortune..

Drain the WH cause you should be doing that annually.

Don't overlook the possibility that the city may have done some work on the water system that sent sediment down the line. Talk to your neighbors.

Do you have an expansion tank on your system? When my expansion tank "bladder" failed, the only indication I had was the black "smoky" sediment like what you describe.

@justalurker - if the city had done work, I think we would have noticed it with the cold water.

@kirkhall - No expansion tank. It's a run-of-the-mill 50-gallon Whirlpool we bought at Lowe's.

It's too hot & humid to deal with draining the water heater tank right now. Once I can do it, I'll watch and see what happens. If it doesn't get better, we'll call the plumber.

The problem has been going on for a couple of years, because I've noticed the same black residue in the FL washer soap dispenser tray. Once I saw it in the Rubbermaid beverage pitcher, I knew it was more than a washing machine issue, and had to be addressed.